PBSI 245 EXAM 1 QUESTIONS WITH VERIFIED
ACCURATE ANSWERS
A statistician tells the producer that the margin of error for a 95% confidence
statement for these data is about plus or minus 2 percentage points. The producer
therefore reports that between 2.8% and 6.8% (that's 4.8% +/- 2%) of all the bags
of spinach are contaminated. This isn't right: only 1% is contaminated. What went
wrong? - Answers -A 95% confidence statement is only right for 95% of all possible
samples. This must be one of the 5% for which one gets an incorrect
conclusion.
Can pleasant aromas help people work more efficiently? Researchers did this study to
find out. Twenty-two students worked a paper-and-pencil maze six times. On three tries,
they
wore a mask with floral scents. On the other three tries, they wore a mask with no scent.
The six tries were done in random order and each used a different maze. The
researchers
found that the subjects took less time to complete the maze when wearing the scented
mask. This study is a(n): - Answers -Experiment
Does St. John's wort have a significant effect in treating major depression? A study
looked at 340 adult outpatients suffering from major depression as measured by their
HAM-D
score, randomly assigning each subject to either a placebo, St. John's wort, or a second
active treatment for comparison.
The study found the difference in treating major depression as measured by
improvement in HAM-D scores between St. John's wort and the placebo was not
statistically
significant. This means that: - Answers -A difference this big could easily occur just by
chance
A U.S. Census Bureau report on the income of Americans say with 90% confidence the
median income of all California households in 2007 was $67,484 with a margin of error
of +/- $375. This means that, - Answers -The census bureau got the result $67,484 +/-
$375 using a message that will cover the true median income 90% of the time when
used repeatedly
The essential difference between an experiment and an observational study is that -
Answers -an experiment imposes treatments on the subjects, but an observational
study does not
The US population census is a census because we attempt to collect data from -
Answers -Every individual in the population
ACCURATE ANSWERS
A statistician tells the producer that the margin of error for a 95% confidence
statement for these data is about plus or minus 2 percentage points. The producer
therefore reports that between 2.8% and 6.8% (that's 4.8% +/- 2%) of all the bags
of spinach are contaminated. This isn't right: only 1% is contaminated. What went
wrong? - Answers -A 95% confidence statement is only right for 95% of all possible
samples. This must be one of the 5% for which one gets an incorrect
conclusion.
Can pleasant aromas help people work more efficiently? Researchers did this study to
find out. Twenty-two students worked a paper-and-pencil maze six times. On three tries,
they
wore a mask with floral scents. On the other three tries, they wore a mask with no scent.
The six tries were done in random order and each used a different maze. The
researchers
found that the subjects took less time to complete the maze when wearing the scented
mask. This study is a(n): - Answers -Experiment
Does St. John's wort have a significant effect in treating major depression? A study
looked at 340 adult outpatients suffering from major depression as measured by their
HAM-D
score, randomly assigning each subject to either a placebo, St. John's wort, or a second
active treatment for comparison.
The study found the difference in treating major depression as measured by
improvement in HAM-D scores between St. John's wort and the placebo was not
statistically
significant. This means that: - Answers -A difference this big could easily occur just by
chance
A U.S. Census Bureau report on the income of Americans say with 90% confidence the
median income of all California households in 2007 was $67,484 with a margin of error
of +/- $375. This means that, - Answers -The census bureau got the result $67,484 +/-
$375 using a message that will cover the true median income 90% of the time when
used repeatedly
The essential difference between an experiment and an observational study is that -
Answers -an experiment imposes treatments on the subjects, but an observational
study does not
The US population census is a census because we attempt to collect data from -
Answers -Every individual in the population
